Cement concrete is widely used in the fields of civil engineering and construction industry at present but such a concrete has faults that it has heavy weight and is brittle. In order to reduce the weight of cement concrete, it is required to introduce fine foams in cement slurry or intermixing light-weight aggregates with cement slurry but such an attempt is poor in practicability since the concrete shows large shrinkage by drying, creep, etc., as well as is inferior in strength. For overcoming these difficulties, a process is employed at present wherein cement concrete is cured under high-temperature and high-pressure saturated vapor. However, the foregoing method is yet insufficient for obtaining high-strength concrete.
As an attempt for greatly increasing the physical or mechanical strength of light-weight concrete, polymer-impregnated concrete is proposed. Such a concrete is prepared by impregnating a light-weight concrete base material with a vinyl monomer and polymerizing the vinyl monomer by the irradiation of radiation or by impregnating a light-weight concrete base material with a vinyl monomer having previously mixed with a polymerization initiator and polymerizing the vinyl monomer by heating. The physical strength of the polymer-impregnated concrete obtained by the foregoing process is greatly improved as compared to the base material as well as the elastic property, chemical resistance, freezing and melting resistance, etc., of the concrete are also improved. However, polymer-impregnated concrete has various problems in productivity. That is, there are such problems that firstly, for effectively improving the strength of the polymer-impregnated concrete, it is required to previously dry the impregnated base material so that the water content thereof becomes lower than 0.5%, secondly, radiation must be treated in one process or a polymerization by heating in another process is accompanied by a large loss of vinyl monomer and is hence uneconomical, thirdly, the working step is complicated, etc. These problems result in increasing the product cost of polymer-impregnated concrete to prevent the practical use of polymer-impregnated concrete.